[Cichoskiss]

So I am in need of engine rebuild (lifter failure). Looking to build up to push over 1000hp with use of f series procharger. Was curious if the lt1 with stock cubes can achieve this? Seems a lot of people jump up to the 416 or 427. I get more displacement more power but curious if it is needed.

[Joshinator99]

Originally Posted by Cichoskiss

So I am in need of engine rebuild (lifter failure). Looking to build up to push over 1000hp with use of f series procharger. Was curious if the lt1 with stock cubes can achieve this? Seems a lot of people jump up to the 416 or 427. I get more displacement more power but curious if it is needed.

I’m at 1230 HP (1059 WHP) now, still 376ci… You don’t need to go 416 to get that power level.

[Ericdared]

Not needed for the power, dunno how many miles you have on your block it may have to be bored anyway due to wear. I'm assuming it was all stock anyway, so you were already going to have to be going with new pistons and rods for the f1 so its not like you are getting a monies savings on the pistons and rods. I guess going 416 would be a bit more money at the machine shop to get the block bored and clearanced but if you are looking to go with a procharged f1 setup I doubt the little bit extra there is going to hurt you.

[radz28]

You don't need to go bigger for that, but more inches is more torque. It's a longer stroke, too, so that's something to thing about, too, if you're serious.

[oldman]

GM says the LT1 crank is limited and hence produced a new crank for 650 HP; hence many guys since the gotta buy a crank anyway go for a stroker. I would think the smaller engine with a stronger crank (and a little more RPM) would be the more dependable way to get where you wanna go. I would go for a custom crank, that said the LT4 crank is minimal for the application, don't even waste time on a LT1 crank. Tell me about lifter failure? Was it the stock AFM or was it the classic LS7 lifter failure?

[Joshinator99]

Originally Posted by oldman

GM says the LT1 crank is limited and hence produced a new crank for 650 HP; hence many guys since the gotta buy a crank anyway go for a stroker. I would think the smaller engine with a stronger crank (and a little more RPM) would be the more dependable way to get where you wanna go. I would go for a custom crank, that said the LT4 crank is minimal for the application, don't even waste time on a LT1 crank. Tell me about lifter failure? Was it the stock AFM or was it the classic LS7 lifter failure?

LME rates their short blocks equipped with the OEM LT1 crank at 1100 WHP, FYI. https://latemodelengines.com/lt1-377-fi-sb.html 650 crank HP is a breeze. I understand what your saying about GM upgrading the LT4 crank, but that’s because they have to warranty idiots running 87 octane in a 650 HP car, IMO. And FWIW I’ve been between 990 and 1230 crank HP for 4 years on the OEM LT1 crank with no issues (I will now go furiously knock on wood lol). I think you’re selling it short.

[radz28]

LT1/LT4 have forged cranks, but I'm not taking anything away from what anyone else has said. Katech ran a stock LT5 out past, like 1400 FWHP or something, and a rod failed - not the crank, if I recall.

What IS concerning on a stock crank, at the 1xxx-power, is, apparently, the half-thrust bearing. I've read/seen some comments about that being a problem, but RPM, for example, takes the stock short blocks past 1xxx-WHP, so... yeah.

Only passing along some stuff I've noticed in the past

[KingLT1]

If you want more cubes I would do a GM L8T 6.6 crank. The L8T crank is good for 1500hp and gets you 401ci.

Either way you don't "need" more cubes to hit 1000. Plenty of stock crank LT1/LT4's have done it. More cubes will allow you to get there with a little less boost. And that is probably a good thing with a F series procharger because they like to chew up belts when spun hard.

[oldman]

Well there is LME, which I don't believe offers a warranty and there is GM that offers a great warranty, the fillet design and the non or minimal drilled last journal make the LT4 crank. Other that that they are similar. Poor fuel has no effect on crank stability. The LT1 crank is made lighter due to drilling of the journal(s) for a little better RPM / revabilty and maybe even a tad fuel economy, the undercut design (going from memory now) is a cheap way to make the crank less prone to cracking under cyclic use, but it DOES make for a weaker crank, the LT4 (going from memory) and all aftermarket cranks are filleted at the bearing surface edge which makes the crank way stronger and less prone to cyclic cracking.

Once again IMO, a LT4 crank is minimum and an aftermarket crank is better. Same goes for the rods, I have the "cheaper" comstar rod, not bad but it ain't no Wiseco boostline job" https://www.maperformance.com/produc...nes-ls6125-927
which would also be the minimal rod I'd go for 1000 HP.

All failure follows a bellshape curve, I'm sure there are bone stock LT1 short blocks out there at 1000 HP for various durations. I build stuff at an expected 50% failure rate over 10 years and/or 100K miles. In my opinion there is way a LT1 crank would do that, I'd give it a 95% or larger failure rate but that would still mean 5 guys out of 100 do it just fine. Lucky at cars unlucky at women is what dad would say. Look in the Honda days guys would boost stone stock B16a (160 HP 1.6 VTEC) to 400 and even 450 dyno queen HP... stone 100% stock tinker toy piston and rods. I've seen it many times, of course there was the inevitable failure, but the engines are / were a dime a dozen. OK maybe they tossed in a .060 cometic head gasket to drop compression... LOL

TSP says there stroker crank is rate to 950 HP and that is a fully filleted crank and minimal rifle drilling of the journals (main and crankpin). So technically even a "real" TSP full fillet forged 4340 medium carbon steel crank is NOT ratted for 1000 HP.


All TSP cranks feature a 2.100" rod pin with a .125" fillet radii and weigh 52 lb. This crank offers excellent consistency and durability, and it is a great choice for customers looking to build an engine up to 950 HP. It does have the non-tapered, standard snout for wet-sump oiling with an 8-bolt rear flange. Be sure to check out the TSP rotating assemblies that we can balance for you as well!

[oldman]

Originally Posted by KingLT1

If you want more cubes I would do a GM L8T 6.6 crank. The L8T crank is good for 1500hp and gets you 401ci.
.

https://katechengines.com/i-30498219...hortblock.html
I don't know what the specs on the crank are but Katech says upto 1200 HP.

[oldman]

Originally Posted by KingLT1

Either way you don't "need" more cubes to hit 1000. Plenty of stock crank LT1/LT4's have done it. More cubes will allow you to get there with a little less boost. And that is probably a good thing with a F series procharger because they like to chew up belts when spun hard.

I'd would for a street fueled car take a smaller engine spun higher say 7200 RPM, the side wall loading is less (better rod angle), there is less chance at detonation at higher RPM, and the engine needs to produce less overall torque to make the 1000 HP and it is torque not HP that blows up the crank and drivetrain. Take two extreme examples. First a twin turbo n the small side heavily overdriven on a 416 CID, that engine may make say 850 ft -lbs of torque (or more like 1000 plus LOL), on the other would be a F centri on a 6.2 turned to 7400 RPM, for the say 1000 Hp it may "only" make 650 ft /lbs, which is stock LT4 level. I'm doing this off the cuff so take this as stated an extreme example. Torque breaks stuff including crank, rods, pistons and drivetrain, and torque is directly related to cylinder pressure where there are further issues on pump fuel. RPM, yea well there are issues there, I feel comfortable at 7200 RPM with high quality valvetrain and a proper ramp / lift camshaft.

One additional benefit to me is the sound of a V8 at full chat shift at 7200 RPM is pure glory, no matter the dyno HP or anything else. Heck I would like to see a true sequential equal length header made for the car (would require two header tubes to pass under the oil pan).

I believe procharger has a 6 rib setup for the F series.

[laynlo15]

A 376 will work great with a FI motor. Bigger inches are better for NA. However the 6.6 is just a little over 400 inches so that would be a great combination as King said. Go for it. The fastest Gen6 Camaro in the country is a twin turbo 377 Cubic inch Lt4 built by LME, like 7.50s@upper170s.

[Joshinator99]

Originally Posted by laynlo15

A 376 will work great with a FI motor. Bigger inches are better for NA. However the 6.6 is just a little over 400 inches so that would be a great combination as King said. Go for it. The fastest Gen6 Camaro in the country is a twin turbo 377 Cubic inch Lt4 built by LME, like 7.50s@upper170s.

Fastest car is a 390 I believe (Justin Keith’s car) which is big bore but stock stroke. Better choice for FI than a 416 stroker IMO.

[radz28]

Thicker walls are why GM went with 6.2 and not 7.0 for LS9.